Regenerated negative electrode material, preparation method thereof, negative electrode plate and lithium ion battery
By using polytannic acid-mediated interface engineering, a highly efficient composite of graphite and nanomaterials was constructed, which solved the problem of volume expansion of retired lithium-ion battery anode materials during charge and discharge processes. This resulted in a high-capacity and long-cycle-life regenerated anode material suitable for the high-value utilization of lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INSTITUTE OF PROCESS ENGINEERING CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2026-03-13
- Publication Date
- 2026-05-15
AI Technical Summary
Existing methods for regenerating retired lithium-ion battery anode materials suffer from high energy consumption and long processes. Graphite anodes have limited capacity, making it difficult to meet high energy density requirements. Furthermore, existing composite materials exhibit severe volume expansion during charge and discharge, resulting in poor cycle performance.
Using polytannic acid (PTA) as a mediator, a stable three-dimensional amorphous carbon skeleton is constructed by generating PTA through self-polymerization reaction. Combined with decommissioned graphite and nanoparticles, a high-efficiency composite material is formed, which buffers volume expansion and improves capacity.
It significantly improves the cycle stability and capacity of regenerated anode materials, achieves high energy density, and the preparation process is environmentally friendly and low-cost, making it suitable for industrial applications.
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Figure CN122051183A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery recycling and regeneration technology, and in particular to a regenerated negative electrode material, its preparation method, and a negative electrode sheet and lithium-ion battery. Background Technology
[0002] With the widespread application of lithium-ion batteries, the number of retired batteries has increased dramatically. Graphite anodes account for approximately 20% of the battery's weight, and their recycling is of great significance for resource conservation and environmental protection. Traditional regeneration methods mainly employ acid washing purification and high-temperature graphitization (2600-3300℃), which suffer from problems such as long processes, high energy consumption, and the introduction of secondary pollution. Furthermore, the theoretical capacity of graphite anodes is limited (372 mAh·g). -1 This makes it difficult to meet the demands of high-energy-density batteries. Furthermore, materials with high theoretical capacity, such as nickel, titanium, and zinc, experience severe volume expansion during charge and discharge, leading to electrode structure damage, short cycle life, and limiting practical applications.
[0003] Electrode performance is not only related to the choice of materials, but also inseparable from the structural design. Composite materials synthesized by introducing foreign elements into graphite tend to agglomerate and undergo drastic volume changes during lithium-ion insertion and extraction, resulting in poor material cycle stability.
[0004] CN113206227A discloses a method for simultaneously recovering waste nickel-cobalt-manganese lithium-ion battery positive and negative electrode materials to prepare carbon-based metal sulfide negative electrode materials. The main steps include: Step 1: Mixing waste positive and negative electrode powders with sublimed sulfur in a certain proportion and mechanically ball-milling to achieve uniform composite; Step 2: High-temperature calcination in a tubular furnace. To ensure safety, the gas exiting the tubular furnace is passed into an alkaline absorption device to neutralize and treat toxic and harmful gases such as sulfur dioxide and sulfur trioxide generated during the reaction, thus achieving the preparation of carbon-based metal sulfide composite materials in one step; Step 3: Lithium extraction from the composite material by water leaching. After drying the leaching residue, it can be directly used as a negative electrode material for sodium-ion batteries. However, the above process has high safety risks, generates a large amount of toxic and harmful gases, and the material performance is difficult to guarantee.
[0005] CN115448308A discloses a method and application for preparing silicon-carbon composite materials using waste lithium-ion battery anodes. The method involves heat-treating, crushing, and sieving the anode sheet to obtain graphite anode powder. The graphite anode powder is then dissolved in an acid solution, stirred, and subjected to solid-liquid separation. The precipitate is collected, washed, and dried to obtain graphite material. Pitch is then dissolved in kerosene to obtain a mixed solution. The graphite material and silicon source are added, and the mixture is stirred until the kerosene completely evaporates, yielding a final mixture. Finally, the mixture is carbonized to obtain a silicon-carbon composite material. However, this process is lengthy, with each step (heat treatment, crushing, acid washing, mixing, and carbonization) increasing equipment, energy consumption, and labor costs. Furthermore, while existing silicon-carbon composite methods can partially alleviate volume expansion, they still face problems such as structural instability, poor conductivity, and poor cycle performance.
[0006] In summary, existing technologies have the following main drawbacks: (1) Traditional regeneration methods are energy-intensive, have long processes, and are costly for industrial applications; (2) Graphite anodes have limited capacity, making it difficult to meet the demand for high energy density; and (3) Existing composite methods have failed to effectively construct a stable conductive framework, limiting the improvement of material performance. Therefore, how to provide an efficient modification method for retired anode materials to obtain anode materials with high capacity and high long-cycle stability has become an urgent problem to be solved. Summary of the Invention
[0007] To address the aforementioned technical problems, the present invention aims to provide a regenerated anode material, its preparation method, and an anode sheet and lithium-ion battery. The regenerated anode material of the present invention utilizes polytannic acid (PTA) to construct a framework to achieve a high-capacity, long-life regenerated anode, thereby improving the capacity and cycle life of the anode material. It is particularly suitable for the high-value recycling of retired graphite anodes.
[0008] To achieve this objective, the present invention adopts the following technical solution:
[0009] In a first aspect, the present invention provides a regenerated anode material, the regenerated anode material comprising carbon-coated nanoparticles and decommissioned anode material; the carbon-coated nanoparticles are dispersed on the surface of the decommissioned anode material; the raw materials for preparing the regenerated anode material include decommissioned anode material, tannic acid and nanoparticles; the decommissioned anode material includes decommissioned graphite.
[0010] This invention employs a mediated interface engineering strategy using polytannic acid (PTA), generated through the self-polymerization of tannic acid, to efficiently regenerate retired anode materials, thereby achieving a significant performance improvement. Specifically, three key raw materials play unique roles and form a synergistic effect during the regeneration process: First, tannic acid, as a functional medium and carbon precursor, constructs a stable three-dimensional amorphous carbon framework through self-polymerization and carbonization, effectively buffering the volume expansion of nanoparticles during cycling, thus significantly improving the cycling stability of the material. Furthermore, its excellent adhesion and pyrolysis characteristics facilitate the construction of a robust composite interface on the surface of retired graphite. Second, retired graphite, as a conductive substrate and structural support, exhibits enhanced hydrophilicity due to its retirement treatment, making it easier to combine with PTA. This provides a stable two-dimensional conductive network and mechanical support for the composite material, ensuring the overall structural integrity of the electrode. Third, high-capacity nano-active materials, as the main capacity-contributing units, are encapsulated within the PTA-derived amorphous carbon framework and uniformly fixed on the graphite substrate surface, thereby suppressing aggregation and volume effects while fully leveraging their high specific capacity. The above three components achieve performance improvement through the following synergistic effect: PTA is polymerized and carbonized in situ on the surface of decommissioned graphite, which not only firmly encapsulates the nano-active materials and restricts their volume changes, but also achieves efficient electron transport by leveraging the conductive network of graphite; the hydrophilic surface of decommissioned graphite enhances the interfacial adhesion of PTA, making the three-dimensional carbon skeleton and the two-dimensional graphite substrate more firmly bonded; and the nanomaterials can fully exert their capacity potential in the highly conductive and highly stable composite structure. The three components work together to achieve a significant improvement in the cycle stability and capacity of the regenerated anode material.
[0011] Compared to other commonly used organic materials in existing technologies, such as dopamine hydrochloride, it has a significant cost advantage and is more likely to form a rough and porous three-dimensional network structure, which can better buffer the volume strain of active substances. On the other hand, materials such as sucrose, although they can be carbonized, do not have the strong adhesive properties inherent in tannic acid. Therefore, they cannot achieve firm modification of the surface of decommissioned graphite or build a stable network at the interface, making it difficult to complete efficient interface engineering.
[0012] The regenerated anode material provided by this invention achieves efficient composite of graphite and nanomaterials through interface engineering, providing a new approach to solving the volume expansion problem of composite materials during charging and discharging. The decommissioned graphite serves as a conductive substrate, while the nanoparticles provide high-capacity active sites, thereby improving the capacity of the regenerated anode material.
[0013] This invention enables the high-value utilization of waste negative electrode material (retired graphite) from retired lithium-ion batteries, which is of great significance for environmental protection and resource conservation.
[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.
[0015] In some embodiments, the nanoparticles include any one or a combination of at least two of nano-nickel oxide, nano-titanium oxide, nano-zinc oxide, nano-iron oxide, or nano-silicon oxide. Typical but non-limiting combinations include combinations of nano-nickel oxide and nano-titanium oxide, nano-nickel oxide and nano-iron oxide, nano-iron oxide and nano-silicon oxide, nano-titanium oxide and nano-zinc oxide, nano-nickel oxide, nano-titanium oxide and nano-zinc oxide, or nano-zinc oxide, nano-iron oxide, and nano-silicon oxide.
[0016] In some embodiments, the mass ratio of nanoparticles to decommissioned anode material in the raw materials for preparing the regenerated anode material is 0.1:1 to 1:1, for example, it can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0017] This invention further controls the mass ratio of nanoparticles to decommissioned anode material in the preparation of regenerated anode materials to be 0.1:1-1:1. The mass ratio of nanoparticles to decommissioned anode material affects the integrity of the overall conductive network, structural stability, and final electrochemical performance of the composite material. If the amount of nanoparticles used is too large, the overloaded nanomaterials will agglomerate severely due to the inability to be effectively dispersed and coated, and at the same time destroy the continuous conductive network formed by the decommissioned graphite substrate, resulting in unstable electrode structure, a surge in interfacial impedance, and rapid deterioration of cycle performance. If the amount of nanoparticles used is too small, its high capacity advantage cannot be fully utilized, and its contribution to the capacity of the decommissioned graphite matrix is limited, resulting in an insignificant improvement in the overall specific capacity of the regenerated anode material and failing to achieve a significant improvement in performance.
[0018] In some embodiments, the mass ratio of tannic acid to decommissioned anode material in the raw materials for preparing the regenerated anode material is 0.1:1 to 1:1, for example, it can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0019] This invention further controls the mass ratio of tannic acid to decommissioned anode material in the preparation of recycled anode material to be 0.1:1-1:1. This mass ratio affects the integrity of the three-dimensional carbon skeleton, the strength of the interfacial bonding, and the structural stability of the composite material. If the amount of tannic acid added is too large, it will destroy the uniformity and dispersion of the recycled anode material, leading to a reduction in battery capacity and a significant decrease in cycle performance. If the amount of tannic acid added is too small, a complete and continuous three-dimensional amorphous carbon coating layer cannot be formed, resulting in a weak interfacial bonding between the nano-active material and the graphite substrate, which is insufficient to effectively buffer the volumetric strain during charge and discharge, severely weakening the improvement effect on the material's structural stability and long-cycle performance, and failing to achieve the technical objective of this invention.
[0020] In a second aspect, the present invention provides a method for preparing the regenerated negative electrode material as described in the first aspect, the method comprising the following steps:
[0021] The decommissioned anode material, nanoparticles, tannic acid, and solvent are mixed and reacted to obtain a product. The product is then carbonized at high temperature to obtain the regenerated anode material.
[0022] In the preparation process of this invention, a stable three-dimensional carbon framework is constructed through the self-polymerization reaction of tannic acid and the carbonization process of polymer, which can effectively limit the volume expansion of nanoparticles and significantly improve cycle stability.
[0023] Polytannic acid (PTA), generated by the self-polymerization of tannic acid, is a soft and adhesive polymer that can effectively bond high-capacity materials to graphite substrates. During pyrolysis, PTA induces two spatially confined localized shrinkage steps. The first occurs at lower temperatures, where the material shrinks significantly in the direction perpendicular to the sheets (longitudinal direction), due to π-π stacking and dehydration between molecular layers, forming nanosheet structures. The second occurs at higher temperatures, dominated by carbonization, and is constrained in-plane in three dimensions, ultimately forming defective carbon materials with macroporous structures and excellent electrical conductivity. Based on these properties, PTA can serve as a linking phase, promoting ion / electron conduction and synergistically leveraging the advantages of both graphite and high-capacity materials. This allows for the construction of high-capacity composite materials while maintaining electrode structural stability. The PTA framework effectively limits the expansion of high-capacity nanomaterials, significantly extending their lifespan.
[0024] The preparation method of the present invention has a simple process, does not require high-temperature graphitization at 2600℃-3300℃ or strong acid treatment, has low energy consumption, is environmentally friendly, and is suitable for industrial application.
[0025] In some embodiments, during the reaction process, a buffer solution is used to adjust the pH of the reaction system to 6-9, for example, 6, 6.5, 7, 7.5, 8, 8.5 or 9, but not limited to the listed values. Other unlisted values within the range are also applicable.
[0026] This invention controls the pH of the reaction system to 6-9 using a buffer solution. The pH of the reaction system affects the polymerization kinetics of tannic acid and its adhesion behavior on the surface of decommissioned graphite. If the pH of the reaction system is too high, tannic acid will undergo excessively rapid oxidative self-polymerization, forming a large number of loose and uneven aggregates instead of forming a dense and continuous coating layer on the graphite surface. This weakens the stability of the interfacial bonding and ultimately damages the rate performance and cycle life of the material. If the pH of the reaction system is too low, the tannic acid molecules will be too protonated, and the dissociation of its phenolic hydroxyl groups and the hydrogen bonding interaction with oxygen-containing functional groups on the graphite surface will be significantly inhibited. At the same time, the effective coordination with metal ions will be hindered, resulting in insufficient interfacial bonding, a loose coating layer, and an inability to construct a stable three-dimensional carbon framework to buffer volume changes.
[0027] The decommissioned anode material used as a raw material in this invention can be obtained using conventional methods in the prior art. For example, the decommissioned anode material is prepared by the following method:
[0028] The retired lithium-ion battery graphite anode sheet is pretreated with sodium chloride solution, then immersed in an organic solvent (NMP solution), the graphite solid is separated by filtration or centrifugation, washed with fresh NMP or ethanol to remove residual PVDF, the obtained material is calcined to remove organic matter, and then rinsed with deionized water to obtain retired graphite anode material.
[0029] In some embodiments, the buffer solution used in the reaction process includes a Tris buffer solution.
[0030] In some embodiments, the reaction is a self-polymerization reaction, and the self-polymerization reaction time is 6h-24h, for example, it can be 6h, 8h, 10h, 12h, 15h, 18h, 20h, 22h, 23h or 24h, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0031] In some embodiments, the solvent includes water.
[0032] In some embodiments, the high-temperature carbonization temperature is 600℃-1000℃, for example, it can be 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃ or 1000℃, but is not limited to the listed values, and other unlisted values within the range are also applicable.
[0033] This invention further controls the high-temperature carbonization temperature to 600℃-1000℃. The high-temperature carbonization temperature affects the graphitization degree, mechanical strength, and interfacial bonding strength between the tannic acid-derived amorphous carbon skeleton and the decommissioned graphite substrate. If the high-temperature carbonization temperature is too high, it will lead to excessive graphitization of the carbon skeleton and produce hard and brittle properties. At the same time, it may destroy the constructed three-dimensional network structure, weaken its ability to buffer volume expansion, and the shrinkage of the carbon skeleton at high temperature may cause cracking, resulting in the peeling off of the coating layer, thereby seriously damaging the cycle stability and structural integrity of the material. If the high-temperature carbonization temperature is too low, the prepared regenerated negative electrode material will expand during charge and discharge, resulting in poor cycle stability.
[0034] In some embodiments, the high-temperature carbonization time is 6h-18h, for example, it can be 6h, 8h, 10h, 12h, 15h, 16h or 18h, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0035] In some embodiments, the heating rate of the high-temperature carbonization is 2℃ / min-10℃ / min, for example, it can be 2℃ / min, 5℃ / min, 6℃ / min, 8℃ / min or 10℃ / min, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0036] In some embodiments, the atmosphere for high-temperature carbonization is an inert atmosphere, which includes a nitrogen atmosphere.
[0037] As a preferred embodiment of the preparation method of the present invention, the preparation method includes the following steps:
[0038] Retired graphite and water were mixed and ultrasonically dispersed to obtain a graphite solution. Nanoparticles and tannic acid were added to the graphite solution at a mass ratio of nanoparticles to retired graphite of 0.1:1-1:1 and a mass ratio of tannic acid to retired graphite of 0.1:1-1:1. The pH was adjusted to 6-9 using Tris buffer solution, and the mixture was stirred for 6-24 hours to complete the self-polymerization reaction. The product was obtained by filtration, washing, and drying.
[0039] The product was heated to 600℃-1000℃ in an argon atmosphere at a heating rate of 2℃ / min-10℃ / min, and carbonized at high temperature for 6h-18h to obtain the regenerated negative electrode material.
[0040] Thirdly, the present invention provides a negative electrode sheet, the negative electrode sheet comprising the regenerated negative electrode material described in the first aspect.
[0041] Fourthly, the present invention provides a lithium-ion battery, the lithium-ion battery comprising the negative electrode sheet described in the third aspect.
[0042] The lithium-ion battery provided by this invention uses recycled anode material obtained by modifying retired graphite as the anode. This alleviates the volume expansion problem and exhibits excellent discharge capacity and long cycle life. At 0.1C, the discharge capacity of the retired graphite material is increased from 289 mAh·g. -1 Increased to greater than 400mAh·g -1 .
[0043] The numerical range described in this invention includes not only the point values listed above, but also any point values within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values included in the range.
[0044] Compared with the prior art, the present invention has at least the following beneficial effects:
[0045] (1) The recycled anode material provided by this invention achieves efficient composite of graphite and nanomaterials through polytannic acid (PTA) mediated interface engineering, providing a new approach to solving the volume expansion problem of composite materials during charging and discharging; retired graphite serves as a conductive substrate; nanoparticles provide high-capacity active sites, which can improve the capacity of the recycled anode material. This invention utilizes retired lithium-ion battery anode waste (retired graphite) in a high-value manner, which is of great significance for environmental protection and resource conservation.
[0046] (2) In the preparation process of this invention, a stable three-dimensional carbon skeleton is constructed through the self-polymerization reaction of tannic acid and the carbonization process of polymer, which can effectively limit the volume expansion of nanoparticles and significantly improve cycle stability. The preparation method is simple, does not require high-temperature graphitization at 2600℃-3300℃ or strong acid treatment, has low energy consumption, is environmentally friendly, and is suitable for industrial application.
[0047] (3) The lithium-ion battery provided by the present invention uses recycled negative electrode material after modification of retired graphite as the negative electrode. The resulting lithium-ion battery alleviates the volume expansion problem and exhibits excellent discharge capacity and long cycle life. At 0.1C, the discharge capacity of the retired graphite raw material is reduced from 289 mAh·g -1 Increased to greater than 400mAh·g -1 . Attached Figure Description
[0048] Figure 1 This is a SEM image of the regenerated negative electrode material provided in Embodiment 1 of the present invention;
[0049] Figure 2 This is the EDS energy spectrum of the regenerated negative electrode material provided in Embodiment 1 of the present invention. Detailed Implementation
[0050] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0051] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.
[0052] Unless otherwise specified, all reagents and consumables used in the following examples and comparative examples were purchased from conventional reagent manufacturers in the art; unless otherwise specified, the experimental methods and techniques used were conventional methods and techniques in the art.
[0053] Example 1
[0054] This embodiment provides a regenerated negative electrode material, which includes carbon-coated silicon oxide nanoparticles and decommissioned graphite;
[0055] The method for preparing the regenerated negative electrode material provided in this embodiment includes the following steps:
[0056] Retired graphite and water were mixed and ultrasonically dispersed to obtain a graphite solution. The nanoparticles and tannic acid were added to the graphite solution according to the mass ratio of silica nanoparticles to retired graphite of 0.3:1 and the mass ratio of tannic acid to retired graphite of 0.3:1. The pH was adjusted to 8.0 using Tris buffer. After stirring for 18 hours, the self-polymerization reaction was completed. The product was obtained by filtration, washing and drying.
[0057] The product was heated to 800°C in an argon atmosphere at a heating rate of 5°C / min and carbonized at high temperature for 8 hours to obtain the regenerated negative electrode material.
[0058] SEM images of the prepared regenerated anode material are shown below. Figure 1 As shown, from Figure 1 As can be seen, polytannic acid (PTA) is coated on the surface of decommissioned graphite after high-temperature carbonization, and nano-silicon is filled in the carbon skeleton and distributed evenly.
[0059] Figure 2 The EDS elemental mapping image shows that the composite electrode contains Si and C elements, which proves the successful adhesion of nano-silicon to the graphite substrate and PTA framework.
[0060] Example 2
[0061] This embodiment provides a regenerated negative electrode material, which includes carbon-coated nickel oxide nanoparticles and decommissioned graphite;
[0062] The method for preparing the regenerated negative electrode material provided in this embodiment includes the following steps:
[0063] Retired graphite and water were mixed and ultrasonically dispersed to obtain a graphite solution. The nanoparticles and tannic acid were added to the graphite solution according to the mass ratio of nickel oxide nanoparticles to retired graphite of 0.2:1 and the mass ratio of tannic acid to retired graphite of 0.6:1. The pH was adjusted to 7.0 using Tris buffer and stirred for 12 hours to complete the self-polymerization reaction. The product was obtained by filtration, washing and drying.
[0064] The product was heated to 700°C in an argon atmosphere at a heating rate of 3°C / min and carbonized at high temperature for 10 hours to obtain the regenerated anode material.
[0065] Example 3
[0066] This embodiment provides a regenerated negative electrode material, which includes carbon-coated nickel oxide nanoparticles and decommissioned graphite;
[0067] The method for preparing the regenerated negative electrode material provided in this embodiment includes the following steps:
[0068] Retired graphite and water were mixed and ultrasonically dispersed to obtain a graphite solution. Nickel oxide nanoparticles and tannic acid were added to the graphite solution at a mass ratio of 0.8:1 for nickel oxide nanoparticles and 1:1 for tannic acid. The pH was adjusted to 9 using Tris buffer, and the mixture was stirred for 6 hours to complete the self-polymerization reaction. The product was obtained by filtration, washing, and drying.
[0069] The product was heated to 600℃ in an argon atmosphere at a heating rate of 10℃ / min and carbonized at high temperature for 18h to obtain the regenerated negative electrode material.
[0070] Example 4
[0071] This embodiment provides a regenerated negative electrode material. The only difference from Embodiment 1 is that, when preparing this regenerated negative electrode material, the mass ratio of tannic acid to decommissioned graphite is 2:1, while the other steps remain unchanged.
[0072] Example 5
[0073] This embodiment provides a regenerated negative electrode material. The only difference from Embodiment 1 is that, when preparing this regenerated negative electrode material, the mass ratio of tannic acid to decommissioned graphite is 0.05:1, while the other steps remain unchanged.
[0074] Example 6
[0075] This embodiment provides a regenerated negative electrode material. The only difference from Embodiment 1 is that the calcination temperature is changed from 800°C to 200°C when preparing the regenerated negative electrode material, while the other steps remain unchanged.
[0076] Example 7
[0077] This embodiment provides a regenerated negative electrode material. The only difference from Embodiment 1 is that the calcination temperature is changed from 800℃ to 1300℃ when preparing the regenerated negative electrode material, while the other steps remain unchanged.
[0078] Example 8
[0079] This embodiment provides a regenerated anode material. The only difference from Embodiment 1 is that the mass ratio of silicon oxide nanoparticles to decommissioned graphite is 2:1 when preparing the regenerated anode material, while the other steps remain unchanged.
[0080] Example 9
[0081] This embodiment provides a regenerated anode material. The only difference from Embodiment 1 is that the mass ratio of silicon oxide nanoparticles to decommissioned graphite is 0.05:1 when preparing the regenerated anode material, while the other steps remain unchanged.
[0082] Comparative Example 1
[0083] This comparative example provides a recycled anode material, which differs from Example 1 only in that the recycled anode material is original decommissioned graphite powder, i.e., without subsequent modification treatment.
[0084] Comparative Example 2
[0085] This comparative example provides a regenerated anode material, which differs from Example 1 only in that no nanoparticles are added during the preparation of this regenerated anode material.
[0086] Comparative Example 3
[0087] This comparative example provides a regenerated negative electrode material, which differs from Example 1 only in that, when preparing this regenerated negative electrode material, tannic acid is replaced with an equal mass of dopamine hydrochloride.
[0088] Comparative Example 4
[0089] This comparative example provides a negative electrode material, which is uncirculated graphite powder, i.e., fresh graphite powder (Kelode) that is purchased directly.
[0090] Application Example 1
[0091] The electrochemical performance of the samples was tested using a half-cell method. The specific steps are as follows: The regenerated negative electrode material prepared in Example 1, acetylene black, and PVDF were mixed in NMP at a mass ratio of 8:1:1 and stirred for 8 hours until a uniform slurry was formed. This slurry was then uniformly coated onto a copper foil using a scraper to serve as the working electrode (14.0 mm in diameter). Subsequently, the electrode coated with the slurry was dried in an oven at 80°C for 0.5 hours, and then placed in a vacuum oven at 100°C for 12 hours.
[0092] The half-cell was assembled in a glove box using a polypropylene porous membrane as the separator. A 1.0M LiPF6 solution (ethylene carbonate, diethyl carbonate, and methyl carbonate in a volume ratio of 1:1:1) was used as the electrolyte. A lithium sheet was used as the counter electrode. Constant current charge-discharge cycle tests were conducted in a multi-channel battery system to evaluate the half-cell's performance.
[0093] Application Examples 2-9
[0094] Application Examples 2-9 each provide a lithium-ion battery. The only difference between the lithium-ion battery and Application Example 1 is that, in the preparation process of the negative electrode sheet, the regenerated negative electrode material obtained in Example 1 is replaced with the regenerated negative electrode material obtained in Examples 2-9; the other positive electrode sheet, electrolyte and separator are the same as in Application Example 1.
[0095] Comparative Application Examples 1-4
[0096] Comparative Application Examples 1-4 each provide a lithium-ion battery. The only difference between the lithium-ion battery and Application Example 1 is that, in the preparation process of the negative electrode sheet, the regenerated negative electrode material obtained in Example 1 is replaced with the negative electrode material obtained in Comparative Examples 1-4; the other positive electrode sheet, electrolyte and separator are the same as in Application Example 1.
[0097] test:
[0098] The lithium-ion batteries prepared in the corresponding use cases and comparative application examples were tested at 0.01-2.0V (vs. Li / Li). + Cyclic performance tests were conducted within the voltage range of [specific voltage range]. The tests were performed at room temperature (25°C) and repeated to ensure data reliability. The test results are shown in Table 1 below.
[0099] Table 1
[0100]
[0101] The test results show that:
[0102] (1) As can be seen from Application Examples 1-3, this invention achieves efficient composite of graphite and nanomaterials through polytannic acid (PTA) mediated interface engineering, providing a new approach to solving the volume expansion problem in the charging and discharging process of composite materials; retired graphite serves as a conductive substrate; nanoparticles provide high-capacity active sites, which can improve the capacity of regenerated anode materials. At 0.1C, the discharge capacity of retired graphite raw materials is increased from 289 mAh·g -1 Increased to greater than 400mAh·g -1 This invention enables the high-value utilization of waste negative electrode material (retired graphite) from retired lithium-ion batteries, which is of great significance for environmental protection and resource conservation.
[0103] (2) By comparing Application Example 1 with Application Examples 4-5, it can be seen that the present invention further controls the mass ratio of tannic acid to retired anode material in the raw materials for preparing the recycled anode material to be 0.1:1-1:1. The mass ratio of tannic acid to retired anode material affects the integrity of the three-dimensional carbon skeleton, the strength of the interface bonding and the structural stability of the composite material. If the amount of tannic acid added is too large, it will destroy the uniformity and dispersion of the recycled anode material, resulting in a decrease in battery capacity and a significant decrease in cycle performance. If the amount of tannic acid added is too small, it will be impossible to form a complete and continuous three-dimensional amorphous carbon coating layer, resulting in a weak interface bonding between the nano-active material and the graphite substrate, and it is insufficient to effectively buffer the volume strain during the charging and discharging process, which seriously weakens the effect of improving the structural stability and long cycle performance of the material, and fails to achieve the technical purpose of the present invention.
[0104] (3) By comparing Application Example 1 with Application Examples 6-7, it can be seen that the present invention further controls the high-temperature carbonization temperature to 600℃-1000℃. The high-temperature carbonization temperature affects the graphitization degree, mechanical strength and interfacial bonding strength of the amorphous carbon skeleton derived from tannic acid. If the high-temperature carbonization temperature is too high, it will cause the carbon skeleton to be over-graphitized and produce hard and brittle characteristics. At the same time, it may destroy the constructed three-dimensional network structure, weaken its ability to buffer volume expansion, and the carbon skeleton shrinkage at high temperature may cause cracking, resulting in the coating layer falling off, thereby seriously damaging the cycle stability and structural integrity of the material. If the high-temperature carbonization temperature is too low, the prepared regenerated negative electrode material will expand during charging and discharging, resulting in poor cycle stability.
[0105] (4) By comparing Application Example 1 with Application Examples 8-9, it can be seen that in the preparation of the regenerated anode material of the present invention, the mass ratio of nanoparticles to retired anode material is 0.1:1-1:1. The mass ratio of nanoparticles to retired anode material affects the integrity of the overall conductive network, structural stability and final electrochemical performance of the composite material. If the amount of nanoparticles used is too large, the overloaded nanomaterials will be severely agglomerated because they cannot be effectively dispersed and coated, and at the same time destroy the continuous conductive network formed by the retired graphite substrate, resulting in unstable electrode structure, surge in interface impedance and rapid deterioration of cycle performance. If the amount of nanoparticles used is too small, its high capacity advantage cannot be fully utilized, and its contribution to the capacity of the retired graphite matrix is limited, resulting in an insignificant improvement in the overall specific capacity of the regenerated anode material and failure to achieve significant performance improvement.
[0106] (5) As can be seen from Application Example 1 and Comparative Application Example 1-Comparative Application Example 3, when tannic acid or nanoparticles are not introduced, it is impossible to achieve the technical effect of simultaneously improving capacity and cycle life by constructing a stable composite structure through interface engineering. It can be seen that the three have a synergistic effect of constructing an integrated stable architecture of "conductive substrate-interface layer-active unit". However, if tannic acid is replaced with dopamine hydrochloride, due to its high cost and difficulty in forming a three-dimensional network carbon skeleton with sufficient thickness and mechanical strength on the surface of decommissioned graphite, the excellent effect of the present invention cannot be achieved.
[0107] (6) As can be seen from Application Example 1 and Comparative Application Example 4, the present invention achieves efficient composite of graphite and nanomaterials through polytannic acid (PTA) mediated interface engineering, thereby increasing the discharge capacity of decommissioned graphite raw materials from 289 mAh·g -1 Increased to greater than 400mAh·g -1 Compared to new graphite powder, its discharge capacity and capacity retention rate are significantly improved, achieving not only a full recovery of the performance of retired anode materials but also surpassing the key electrochemical indicators of new materials, demonstrating the technological effectiveness of upgraded regeneration.
[0108] In summary, this invention achieves efficient composite materialization of graphite and nanomaterials through polytannic acid (PTA)-mediated interface engineering, providing a new approach to solving the volume expansion problem during the charge-discharge process of composite materials. Retired graphite serves as the conductive substrate, while nanoparticles provide high-capacity active sites, enabling an increase in the capacity of the regenerated anode material. At 0.1C, the discharge capacity of the retired graphite raw material is increased from 289 mAh·g. -1 Increased to greater than 400mAh·g -1 This invention enables the high-value utilization of waste negative electrode material (retired graphite) from retired lithium-ion batteries, which is of great significance for environmental protection and resource conservation.
[0109] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.
Claims
1. A regenerated negative electrode material, characterized in that, The regenerated anode material includes carbon-coated nanoparticles and decommissioned anode materials; The carbon-coated nanoparticles are dispersed on the surface of the decommissioned anode material; The raw materials for preparing the regenerated anode material include decommissioned anode material, tannic acid, and nanoparticles. The decommissioned anode material includes decommissioned graphite.
2. The regenerated negative electrode material according to claim 1, characterized in that, The nanoparticles include any one or a combination of at least two of nano-nickel oxide, nano-titanium oxide, nano-zinc oxide, nano-iron oxide, or nano-silicon oxide. And / or, in the raw materials for preparing the recycled negative electrode material, the mass ratio of nanoparticles to decommissioned negative electrode material is 0.1:1-1:1; And / or, in the raw materials for preparing the regenerated negative electrode material, the mass ratio of tannic acid to decommissioned negative electrode material is 0.1:1-1:
1.
3. A method for preparing the regenerated negative electrode material as described in claim 1 or 2, characterized in that, The preparation method includes the following steps: The decommissioned anode material, nanoparticles, tannic acid, and solvent are mixed and reacted to obtain a product. The product is then carbonized at high temperature to obtain the regenerated anode material.
4. The preparation method according to claim 3, characterized in that, During the reaction process, a buffer solution is used to adjust the pH of the reaction system to 6-9.
5. The preparation method according to claim 4, characterized in that, During the reaction, the buffer solution includes Tris buffer.
6. The preparation method according to any one of claims 3-5, characterized in that, The reaction is a self-polymerization reaction, and the self-polymerization reaction takes 6-24 hours. And / or, the solvent includes water.
7. The preparation method according to any one of claims 3-6, characterized in that, The high-temperature carbonization temperature is 600℃-1000℃; And / or, the high-temperature carbonization time is 6h-18h.
8. The preparation method according to any one of claims 3-7, characterized in that, The preparation method includes the following steps: Retired graphite and water were mixed and ultrasonically dispersed to obtain a graphite solution. Nanoparticles and tannic acid were added to the graphite solution at a mass ratio of nanoparticles to retired graphite of 0.1:1-1:1 and a mass ratio of tannic acid to retired graphite of 0.1:1-1:
1. The pH was adjusted to 6-9 using Tris buffer solution, and the mixture was stirred for 6-24 hours to complete the self-polymerization reaction. The product was obtained by filtration, washing, and drying. The product was heated to 600℃-1000℃ in an argon atmosphere at a heating rate of 2℃ / min-10℃ / min, and carbonized at high temperature for 6h-18h to obtain the regenerated negative electrode material.
9. A negative electrode sheet, characterized in that, The negative electrode sheet comprises the regenerated negative electrode material as described in claim 1 or 2.
10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the negative electrode sheet as described in claim 9.